Liquid crystal display

ABSTRACT

A liquid crystal display includes a first substrate, a first electrode disposed on the first substrate, a second electrode which is disposed on the first substrate and overlaps the first electrode, an insulating layer interposed between the first electrode and the second electrode, a first alignment layer disposed on the first electrode and the second electrode, a second substrate facing the first substrate, and a second alignment layer disposed on the second substrate, where a first resistivity value of the first alignment layer is smaller than a second resistivity value of the second alignment layer.

This application is a divisional of U.S. patent application Ser. No.14/658,502, filed on Mar. 16, 2015, which claims priority to and thebenefit of Korean Patent Application No. 10-2014-0033644, filed on Mar.21, 2014, and all the benefits accruing therefrom under 35 U.S.C. §119,the entire contents of which are incorporated herein by reference.

BACKGROUND (a) Field

The invention relates to a liquid crystal display.

(b) Description of the Related Art

A liquid crystal display (“LCD”) is one of the most widely used flatpanel displays, and displays images by applying voltages tofield-generating electrodes to generate an electric field in an LC layerthat determines orientations of LC molecules therein to adjustpolarization of incident light.

The LCD has a merit in that light weight and thin formation thereof areeasily obtained. However the LCD has a drawback in that lateralvisibility is lower than front visibility, and liquid crystalarrangements and driving methods of various types have been developed tosolve the drawback. To realize a wide viewing angle, an LCD including apixel electrode and a reference electrode on one substrate has beenspotlighted.

In the LCD, at least one of two field generating electrodes among apixel electrode and a common electrode has a plurality of cutoutsdefined therein, and a plurality of branch electrodes defined by theplurality of cutouts.

SUMMARY

When disposing two field generating electrodes on one substrate in aliquid crystal display (“LCD”), after applying voltage to the fieldgenerating electrode, although the applied voltage is turned off, amolecular ion is not discharged such that an unnecessary electric fieldis maintained, thereby generating an afterimage.

The invention provides a LCD including two field generating electrodeson one substrate thereof, and preventing an afterimage.

An LCD according to an exemplary embodiment of the invention includes afirst substrate, a first electrode disposed on the first substrate, asecond electrode which is disposed on the first substrate and overlapsthe first electrode, an insulating layer interposed between the firstelectrode and the second electrode, a first alignment layer disposed onthe first electrode and the second electrode, a second substrate facingthe first substrate, and a second alignment layer disposed on the secondsubstrate, where a first resistivity value of the first alignment layeris smaller than a second resistivity value of the second alignmentlayer.

A ratio of the second resistivity value of the second alignment layer tothe first resistivity value of the first alignment layer may be about 10to about 100.

A first thickness of the first alignment layer is larger than a secondthickness of the second alignment layer.

A ratio of the second thickness of the second alignment layer to thefirst thickness of the first alignment layer is about 0.3 to about 0.7.

One of the first electrode and the second electrode may have a pluralityof cutouts defined therein.

A color filter disposed between the second substrate and the secondalignment layer may be further included.

An LCD according to another exemplary embodiment of the inventionincludes a first substrate, a first electrode disposed on the firstsubstrate, a second electrode which is disposed on the first substrateand overlaps the first electrode, an insulating layer interposed betweenthe first electrode and the second electrode, a first alignment layerdisposed on the first electrode and the second electrode, a secondsubstrate facing the first substrate, and a second alignment layerdisposed on the second substrate, where a first thickness of the firstalignment layer is larger than a second thickness of the secondalignment layer.

According to the LCD according to an exemplary embodiment of theinvention, two field generating electrodes may be disposed on onesubstrate, and the afterimage may be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other exemplary embodiments, advantages and features ofthis disclosure will become more apparent by describing in furtherdetail exemplary embodiments thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic cross-sectional view of an exemplary embodiment ofa liquid crystal display (“LCD”) according to the invention.

FIG. 2 is a plan view of an exemplary embodiment of an LCD according tothe invention.

FIG. 3 is a cross-sectional view of the LCD of FIG. 2 take along line

FIG. 4 is a plan view of another exemplary embodiment of an LCDaccording to the invention.

FIG. 5 is a cross-sectional view of the LCD of FIG. 4 take along lineV-V.

DETAILED DESCRIPTION

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. As those skilled in the art would realize, thedescribed embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the invention.

The invention now will be described more fully hereinafter withreference to the accompanying drawings, in which various embodiments areshown. This invention may, however, be embodied in many different forms,and should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. Like reference numerals refer tolike elements throughout.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on,” “connected to” or “coupled to” another element, it can bedirectly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected to” or “directly coupled to” another element,there are no intervening elements present.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the invention.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example In an exemplaryembodiment, if when the device in the figures is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms, “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “includes”and/or “including”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Next, a liquid crystal display (“LCD”) according to an exemplaryembodiment of the invention will be described with reference toaccompanying drawings.

First, an LCD according to an exemplary embodiment of the invention willbe described with reference to FIG. 1. FIG. 1 is a schematiccross-sectional view of an LCD according to an exemplary embodiment ofthe invention.

Referring to FIG. 1, the LCD according to an exemplary embodiment of theinvention includes a first display panel 100 and a second display panel200 facing each other, and a liquid crystal layer 3 interposedtherebetween.

The first display panel 100 includes a first electrode 130 and a secondelectrode 190 disposed on a first substrate 110 and overlapping eachother via an insulating layer 80 interposed therebetween, and a firstalignment layer 11 disposed on the first electrode 130 and the secondelectrode 190.

The second display panel 200 includes a color filter 230, an overcoat250, and a second alignment layer 21 disposed on a second substrate 210.In an exemplary embodiment, resistivity of the first alignment layer 11is smaller than resistivity of the second alignment layer 21. In theexemplary embodiment, a ratio of the resistivity of the second alignmentlayer 21 to the resistivity of the first alignment layer 11 is about 10to about 100, for example.

In an exemplary embodiment, a first thickness D1 of the first alignmentlayer 11 is smaller than a second thickness D2 of the second alignmentlayer 21. In the exemplary embodiment, a ratio (D2/D1) of the secondthickness D2 of the second alignment layer 21 to the first thickness D1of the first alignment layer 11 is about 0.3 to about 0.7.

In an exemplary embodiment, the resistivity value of the secondalignment layer 21 may be larger than about 10E14, and the resistivityvalue of the first alignment layer 11 may be smaller than about 10E13.In an exemplary embodiment, the resistivity value of the secondalignment layer 21 may be larger than about 10E16, and the resistivityvalue of the first alignment layer 11 may be smaller than about 10E14,for example. In an exemplary embodiment, the second alignment layer 21may an inorganic material.

Voltages are respectively applied to the first electrode 130 and thesecond electrode 190 to generate an electric field F, and liquid crystalmolecules of the liquid crystal layer 3 are rotated by the electricfield F.

After the voltages respectively applied to the first electrode 130 andthe second electrode 190 are blocked, a charge C that is charged to thefirst electrode 130 and the second electrode 190 is not discharged suchthat the unnecessary electric field may be applied to the liquid crystallayer 3 by the charge C. The unnecessary charge may inflow from animpurity of the color filter 230 provided at the second display panel200.

According to an exemplary embodiment of the LCD of the invention, theresistivity value of the first alignment layer 11 disposed on the firstdisplay panel 100 is substantially small and the first thickness D1 ofthe first alignment layer 11 is substantially large. Also, theresistivity value of the second alignment layer 21 is substantiallylarge and the second thickness D2 of the second alignment layer 21 issubstantially small. In an exemplary embodiment, the ratio of theresistivity of the second alignment layer 21 to the resistivity of thefirst alignment layer 11 is about 10 to about 100, and the ratio (D2/D1)of the second thickness D2 of the second alignment layer 21 to the firstthickness D1 of the first alignment layer 11 is about 0.3 to about 0.7,for example.

The resistivity value of the first alignment layer 11 disposed on thefirst display panel 100 is substantially small and the first thicknessD1 of the first alignment layer 11 is substantially large such that thecharged charge C may be easily discharged. When the resistivity issubstantially small, the charge may be easily moved such that thecharged charge C may be easily discharged. Also, when the firstthickness D1 is substantially large, the capacitance is decreased suchthat the charged charge C may be easily discharged.

The resistivity value of the second alignment layer 21 disposed in thesecond display panel 200 is substantially large and the second thicknessD2 of the second alignment layer 21 is substantially small such that theimpurity emitted from the color filter 230 of the second display panel200 is difficult to exhaust outside thereof. In detail, the resistivityvalue of the second alignment layer 21 is substantially large such thatit is difficult for the charge to be moved, and the second thickness D2is substantially small such that the capacitance is large and it isdifficult for the unnecessary charge to be moved. Accordingly, theunnecessary charge does not inflow from the impurity that may begenerated from an organic layer, such as the color filter 230, providedat the second display panel 200.

As described above, for the LCD according to an exemplary embodiment ofthe invention, by controlling the resistivity value and the thickness ofthe first alignment layer 11 provided in the first display panel 100 andthe second alignment layer 21 disposed in the second display panel 200,the charged charge C in the first display panel 100 including two fieldgenerating electrodes may be easily discharged, and flow of theunnecessary charge that may be generated from the impurity in the seconddisplay panel 200 may be reduced or effectively prevented. Accordingly,application of the unnecessary electric field to the liquid crystallayer by the charged charge may be reduced or effectively prevented,thereby preventing the afterimage due to the unnecessary electric field.

Next, the LCD according to an exemplary embodiment of the invention willbe described with reference to FIGS. 2 and 3. FIG. 2 is a plan view ofan LCD according to an exemplary embodiment of the invention, and FIG. 3is a cross-sectional view of the LCD of FIG. 2 take along line

Referring to FIGS. 2 and 3, an LCD according to an exemplary embodimentof the invention includes a first display panel 100 and a second displaypanel 200 opposite to each other, and a liquid crystal layer 3 injectedbetween the display panels.

Firstly, the first display panel 100 will be described.

In an exemplary embodiment, a gate conductor including a gate line 121is disposed on a first substrate 110 including transparent glass,plastics, or the like.

The gate line 121 includes a gate electrode 124, and a wide end portion(not shown) for connection with another layer or an external drivingcircuit.

In an exemplary embodiment, a gate insulating layer 140 including asilicon nitride (SiNx), a silicon oxide (SiOx), or the like is disposedon the gate conductors 121 and 124. In an exemplary embodiment, the gateinsulating layer 140 may have a multilayered structure including atleast two insulating layers having different physical properties.

In an exemplary embodiment, a semiconductor layer 154 includingamorphous silicon, polysilicon, or the like is disposed on the gateinsulating layer 140. In an exemplary embodiment, the semiconductorlayer 154 may include an oxide semiconductor.

Ohmic contacts 163 and 165 are disposed on the semiconductor layer 154.In an exemplary embodiment, the ohmic contacts 163 and 165 may include amaterial such as n+hydrogenated amorphous silicon in which an n-typeimpurity such as phosphorus is doped at a high concentration, or asilicide. The ohmic contacts 163 and 165 may form a pair to be disposedon the semiconductor layer 154. In the case where the semiconductor 154is the oxide semiconductor, the ohmic contacts 163 and 165 may beomitted.

A data conductor including a data line 171 including a source electrode173 and a drain electrode 175 is disposed on the ohmic contacts 163 and165 and the gate insulating layer 140.

The data line 171 includes a wide end portion (not shown) for connectionwith another layer or an external driving circuit. The data line 171transmits a data signal and mainly extends in a vertical direction tocross the gate line 121.

In an exemplary embodiment, the data line 171 may have a first curvedportion having a curved shape to obtain maximum transmittance of theLCD, and curved portions meet each other at the center region of thepixel area thereby forming a “V” shape. The center region of the pixelarea may further include a second curved portion inclined by the firstcurved portion at a predetermined angle.

In an exemplary embodiment, the first bent portion of the data line 171may be bent so as to form an angle of about 7° with a vertical referenceline y forming an angle of 90° in an extension direction of the gateline 121. In an exemplary embodiment, the second bent portion disposedin the middle region of the pixel region may be further bent so as toform an angle of about 7° to about 15° with the first bent portion.

The source electrode 173 is a portion of the data line 171, and isdisposed on the same line as the data line 171. The drain electrode 175is provided so as to extend in parallel to the source electrode 173.Accordingly, the drain electrode 175 is parallel to a portion of thedata line 171.

The gate electrode 124, the source electrode 173, and the drainelectrode 175 form a thin film transistor (“TFT”) as a switching elementalong with the semiconductor 154, and a channel of the TFT is providedat an exposed portion of the semiconductor 154 between the sourceelectrode 173 and the drain electrode 175.

The LCD according to the exemplary embodiment of the invention mayinclude the source electrode 173 disposed on the same line as the dataline 171 and the drain electrode 175 extending in parallel to the dataline 171 to increase a width of the TFT while the area of the dataconductor is not increased, thus increasing an opening ratio of the LCD.

A first passivation layer 180 n is disposed on the data conductors 171,173, and 175, the gate insulating layer 140, and the exposed portion ofthe semiconductor 154. In an exemplary embodiment, the first passivationlayer 180 n may include an organic insulating material, an inorganicinsulating material, or the like.

A second passivation layer 180 q is disposed on the first passivationlayer 180 n. In another exemplary embodiment, the second passivationlayer 180 q may be omitted. In an exemplary embodiment, the secondpassivation layer 180 q may include the organic material.

A common electrode 270 is disposed on the second passivation layer 180q.

In an exemplary embodiment, the common electrode 270 may have a surfaceshape and be disposed on the entire surface of the substrate 110 to havean overall plate shape, and an opening 138 may be defined in the commonelectrode 270 in a region corresponding to the circumference of thedrain electrode 175. That is, the common electrode 270 may have a flatplate shape.

Common electrodes 270 disposed in adjacent pixels may be connected toeach other to receive a common voltage having a predetermined magnitudesupplied from outside of the display region.

A third passivation layer 180 z is provided on the common electrode 270.In an exemplary embodiment, the third passivation layer 180 z mayinclude an organic insulating material or an inorganic insulatingmaterial.

A pixel electrode 191 is provided on the third passivation layer 180 z.The pixel electrode 191 includes a curved edge which is substantiallyparallel to the first curved portion and the second curved portion ofthe data line 171. A plurality of first cutouts 92 may be defined in thepixel electrode 191, and the pixel electrode 191 includes a plurality offirst branch electrodes 192 defined by the plurality of first cutouts92.

A contact hole 185 is defined in the first passivation layer 180 n, thesecond passivation layer 180 q, and the third passivation layer 180 z toexpose the drain electrode 175. The pixel electrode 191 is physicallyand electrically connected to the drain electrode 175 through thecontact hole 185 so as to be applied with the voltage from the drainelectrode 175.

A first alignment layer 11 is coated on the pixel electrode 191 and thethird passivation layer 180 z. In an exemplary embodiment, the firstalignment layer 11 may be a horizontal alignment layer and may be rubbedin a predetermined direction. However, in the LCD according to anotherexemplary embodiment of the invention, the first alignment layer mayinclude a photoreactive material to be photo-aligned.

Now, the second display panel 200 will be described.

A light blocking member 220 is disposed on a second substrate 210including transparent glass, plastic, or the like. The light blockingmember 220 is also referred to as a black matrix, and blocks lightleakage.

A plurality of color filters 230 is disposed on the second substrate210. Each color filter 230 may uniquely display one of the primarycolors, and an example of the primary colors includes three primarycolors such as red, green, and blue, or yellow, cyan, and magenta.Although it is not illustrated, the color filter may further include acolor filter displaying a combination color of the primary colors, orwhite, other than the primary colors.

An overcoat 250 is disposed on the color filter 230 and the lightblocking member 220. In an exemplary embodiment, the overcoat 250 mayinclude an (organic) insulator, and it protects the color filters 230,prevents the color filters 230 from being exposed, and provides aplanarized surface. In another exemplary embodiment, the overcoat 250may be omitted.

A second alignment layer 21 is disposed on the overcoat 250.

In an exemplary embodiment, the liquid crystal layer 3 includes anematic liquid crystal material having positive dielectric anisotropy.Liquid crystal molecules of the liquid crystal layer 3 are arranged suchthat their longer axes are parallel to the display panels 100 and 200.

The pixel electrode 191 is applied with the data voltage from the drainelectrode 175, and the common electrode 270 is applied with the commonvoltage of a predetermined level from a common voltage application unitdisposed outside the display area.

The pixel electrode 191 and the common electrode 270 as field generatingelectrodes generate an electric field such that the liquid crystalmolecules of the liquid crystal layer 3 disposed thereon are rotated ina direction parallel to the direction of the electric field. Asdescribed above, according to the determined rotation direction of theliquid crystal molecules, the polarization of light passing through theliquid crystal layer is changed.

Resistivity of the first alignment layer 11 is smaller than resistivityof the second alignment layer 21. In an exemplary embodiment, the ratioof the resistivity of the second alignment layer 21 to the resistivityof the first alignment layer 11 is about 10 to about 100, for example.

The first thickness D1 of the first alignment layer 11 is smaller thanthe second thickness D2 of the second alignment layer 21. In anexemplary embodiment, a ratio (D2/D1) of the second thickness D2 of thesecond alignment layer 21 to the first thickness D1 of the firstalignment layer 11 is about 0.3 to about 0.7, for example.

In an exemplary embodiment, the resistivity value of the secondalignment layer 21 may be larger than about 10E14, and the resistivityvalue of the first alignment layer 11 may be smaller than about 10E13,for example. The resistivity value of the second alignment layer 21 maybe larger than about 10E16, and the resistivity value of the firstalignment layer 11 may be smaller than about 10E14. In an exemplaryembodiment, the second alignment layer 21 may include the inorganicmaterial.

As described above, for the LCD according to an exemplary embodiment ofthe invention, by controlling the resistivity value and the thickness ofthe first alignment layer 11 provided at the first display panel 100 andthe second alignment layer 21 provided in the second display panel 200,the charged charge C in the first display panel 100 including two fieldgenerating electrodes may be easily discharged, and flowing in of theunnecessary charge that may be generated from the impurity in the seconddisplay panel 200 may be reduced or effectively prevented. Accordingly,application of the unnecessary electric field by the charged charge tothe liquid crystal layer may be reduced or effectively prevented,thereby preventing the afterimage due to the unnecessary electric field.

Next, the LCD according to another exemplary embodiment of the inventionwill be described with reference to FIGS. 4 and 5. FIG. 4 is a plan viewof an LCD according to an exemplary embodiment of the invention, andFIG. 5 is a cross-sectional view of the LCD of FIG. 4 take along lineV-V.

Referring to FIGS. 4 and 5, the LCD according to the exemplaryembodiment is similar to the LCD according to the exemplary embodimentshown in FIGS. 2 and 3. Detailed descriptions of like constituentelements are omitted.

Referring to FIGS. 4 and 5, the LCD according to the exemplaryembodiment includes the first display panel 100 and the second displaypanel 200 opposite to each other, and the liquid crystal layer 3injected between the display panels.

Firstly, the first display panel 100 will be described.

The gate conductor including the gate line 121 is disposed on the firstsubstrate 110.

In an exemplary embodiment, the gate insulating layer 140 including thesilicon nitride (SiNx), the silicon oxide (SiOx), or the like isdisposed on the gate conductor 121.

The semiconductor 154 is disposed on the gate insulating layer 140.

The ohmic contacts 163 and 165 are disposed on the semiconductor 154.When the semiconductor 154 is the oxide semiconductor, the ohmiccontacts 163 and 165 may be omitted.

The data conductor including the data line 171 including the sourceelectrode 173 and the drain electrode 175 is disposed on the ohmiccontacts 163 and 165 and the gate insulating layer 140.

The pixel electrode 191 is disposed directly on the drain electrode 175.The pixel electrode 191 is disposed in one pixel area while having theflat shape, that is, the plate shape.

A passivation layer 180 is disposed on the data conductors 171, 173, and175, the gate insulating layer 140, the exposed portion of thesemiconductor 154, and the pixel electrode 191. However, in the LCDaccording to another exemplary embodiment of the invention, thepassivation layer 180 may be disposed between the pixel electrode 191and the data line 171, and the pixel electrode 191 may be connected tothe drain electrode 175 through the contact hole (not shown) provided atthe passivation layer 180.

The common electrode 270 is disposed on the passivation layer 180.Adjacent common electrodes 270 are connected to each other and receivethe reference voltage from the common voltage application unit disposedoutside the display area.

The common electrode 270 includes the curved edge which is substantiallyparallel to the first curved portion and the second curved portion ofthe data line 171, and the common electrodes 270 disposed at theadjacent pixels are connected to each other. A plurality of secondcutouts 272 is defined in the common electrode 270 includes, and thecommon electrode 270 includes a plurality of second branch electrodes271 defined by the plurality of second cutouts 272. The first alignmentlayer 11 is coated on the common electrode 270 and the passivation layer180, and although not shown, the first alignment layer 11 may be thehorizontal alignment layer and may be rubbed in a predetermineddirection. However, in the LCD according to another exemplary embodimentof the invention, the first alignment 11 layer may include aphotoreactive material to be photo-aligned.

Now, the second display panel 200 will be described.

The light blocking member 220 is disposed on the second substrate 210. Aplurality of color filters 230 is disposed on the second substrate 210.

The overcoat 250 is disposed on the color filter 230 and the lightblocking member 220. In another exemplary embodiment, the overcoat 250may be omitted.

The second alignment layer 21 may be disposed on the overcoat 250. In anexemplary embodiment, the liquid crystal layer 3 includes a nematicliquid crystal material having positive dielectric anisotropy. Liquidcrystal molecules of the liquid crystal layer 3 are arranged such thattheir longer axes are parallel to the display panels 100 and 200.

The pixel electrode 191 is applied with the data voltage from the drainelectrode 175, and the common electrode 270 is applied with the commonvoltage of the predetermined level from the common voltage applicationunit disposed outside the display area.

The pixel electrode 191 and the common electrode 270 as field generatingelectrodes generate an electrical field such that the liquid crystalmolecules of the liquid crystal layer 3 disposed thereon are rotated ina direction parallel to the direction of the electric field. Asdescribed above, according to the determined rotation direction of theliquid crystal molecules, the polarization of light passing through theliquid crystal layer is changed.

The resistivity of the first alignment layer 11 is smaller than theresistivity of the second alignment layer 21. In an exemplaryembodiment, the ratio of the resistivity of the second alignment layer21 to the resistivity of the first alignment layer 11 is about 10 toabout 100, for example.

The first thickness D1 of the first alignment layer 11 is smaller thanthe second thickness D2 of the second alignment layer 21. In anexemplary embodiment, a ratio (D2/D1) of the second thickness D2 of thesecond alignment layer 21 to the first thickness D1 of the firstalignment layer 11 is about 0.3 to about 0.7, for example.

In an exemplary embodiment, the resistivity value of the secondalignment layer 21 may be larger than about 10E14, and the resistivityvalue of the first alignment layer 11 may be smaller than about 10E13,for example. In an exemplary embodiment, the resistivity value of thesecond alignment layer 21 may be larger than about 10E16, and theresistivity value of the first alignment layer 11 may be smaller thanabout 10E14, for example. The second alignment layer 21 may include theinorganic material.

As described above, for the LCD according to an exemplary embodiment ofthe invention, by controlling the resistivity value and the thickness ofthe first alignment layer 11 provided at the first display panel 100 andthe second alignment layer 21 provided in the second display panel 200,the charged charge C in the first display panel 100 including two fieldgenerating electrodes may be easily discharged, and flowing in of theunnecessary charge that may be generated from the impurity in the seconddisplay panel 200 may be reduced or effectively prevented. Accordingly,application of the unnecessary electric field by the charged charge tothe liquid crystal layer may be reduced or effectively prevented,thereby preventing the afterimage due to the unnecessary electric field.

Next, an experimental example according to the invention will bedescribed with reference to Table 1. In the experimental example, in aconventional LCD, in a first case in which two field generatingelectrodes are disposed on the first substrate, the first alignmentlayer and the second alignment layer are disposed on the first substrateand the second substrate, the resistivity value of the first alignmentlayer and the second alignment layer is about 410E13, and the thicknessthereof is provided at about 1000 angstroms (Å), in the LCD according toan exemplary embodiment of the invention, in a second case in which twofield generating electrodes are disposed on the first substrate, theresistivity value of the first alignment layer disposed on the firstsubstrate and the second alignment layer disposed on the secondsubstrate is about 410E13, the thickness of the first alignment layer isabout 1000 Å, and the thickness of the second alignment layer is about200 Å, and in a third case in which two field generating electrodes aredisposed on the first substrate, the resistivity value of the firstalignment layer disposed on the first substrate is about 410E13, thethickness of the first alignment layer is about 1000 Å, the resistivityvalue of the second alignment layer disposed on the second substrate isabout 610E14, and the thickness of the second alignment layer is about500 Å, and after two field generating electrodes are applied with thesame voltage and are driven for one hour at a temperature of 60 degreesCelsius (° C.), an afterimage result is measured after the passage of 10minutes and the result is shown in Table 1. Except for the resistivityvalue and the thickness of the first alignment layer and the secondalignment layer, the rest of the conditions are all the same.

TABLE 1 Case First case Second case Third case Afterimage 4 degrees 2degrees 1 degree

Here, the 4 degrees as degrees of the afterimage is a degree to which aluminance difference is recognized for each position at a front side anda lateral side, the 2 degrees as degrees of the afterimage is a degreeto which the luminance difference is somehow recognized for eachposition in the front side, and the 1 degree as a degree of theafterimage is a degree to which the luminance difference is notrecognized for each position in the front side.

Referring to Table 1, like the LCD according to an exemplary embodimentof the invention, two field generating electrodes are disposed on thefirst substrate, and the resistivity value and the thickness of thefirst alignment layer disposed on the first substrate and the secondalignment layer disposed on the second substrate are controlled, therebypreventing the afterimage compared with a case that the resistivityvalue and the thickness of the first alignment layer are the same asthose of the second alignment layer.

As described above, for the LCD according to an exemplary embodiment ofthe invention, by controlling the resistivity value and the thickness ofthe first alignment layer 11 provided at the first display panel 100 andthe second alignment layer 21 provided in the second display panel 200,the charged charge C in the first display panel 100 including two fieldgenerating electrodes may be easily discharged, and flowing in of theunnecessary charge that may be generated from the impurity in the seconddisplay panel 200 may be reduced or effectively prevented. Accordingly,application of the unnecessary electric field by the charged charge tothe liquid crystal layer may be reduced or effectively prevented,thereby preventing the afterimage due to the unnecessary electric field.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A liquid crystal display comprising: a firstsubstrate; a first electrode disposed on the first substrate; a secondelectrode which is disposed on the first substrate and overlaps thefirst electrode; an insulating layer interposed between the firstelectrode and the second electrode; a first alignment layer disposed onthe first electrode and the second electrode; a second substrate facingthe first substrate; and a second alignment layer disposed on the secondsubstrate, wherein a first thickness of the first alignment layer islarger than a second thickness of the second alignment layer.
 2. Theliquid crystal display of claim 1, wherein a ratio of the secondthickness of the second alignment layer to the first thickness of thefirst alignment layer is about 0.3 to about 0.7.
 3. The liquid crystaldisplay of claim 2, wherein a first resistivity value of the firstalignment layer is smaller than a second resistivity value of the secondalignment layer.
 4. The liquid crystal display of claim 3, wherein aplurality of cutouts is defined in one of the first electrode and thesecond electrode.
 5. The liquid crystal display of claim 4, furthercomprising a color filter disposed between the second substrate and thesecond alignment layer.
 6. The liquid crystal display of claim 1,wherein a plurality of cutouts is defined in one of the first electrodeand the second electrode.
 7. The liquid crystal display of claim 6,further comprising a color filter disposed between the second substrateand the second alignment layer.